Studies show a large proportion of diet products fail in the long term.Source:Getty Images

BODY image experts want diet products to have to undergo rigorous independent testing to prove they safely keep off the kilos before they are able to hit shelves.

Positive body image advocacy group Endangered Bodies Australia is pushing for the Federal Government to regulate the multi-million-dollar diet industry to make this a ­requirement of its products.

The group’s vice-president, eating disorder psychologist Sarah McMahon, said evidence showed many diet products failed in the long-term and could be dangerous to the user’s health and body confidence. Yet Australians were spending more than $600 million a year on weight-loss foods, supplements and surgery.

Ms McMahon said about 200 body image activists — most health professionals — would be signing an open letter to government calling for a parliamentary inquiry into how regulation could be achieved.

Any regulation should ­require weight-loss products — in particular pills and supplements — to be externally tested before they could be sold, and their outcomes and side effects accurately detailed in labelling and advertising, she said.

The industry was party only to a voluntary code of conduct.

Ms McMahon said while diet products might cause initial weight loss, ­research showed between 95 and 98 per cent failed in the long term.

As a psychologist at Body Matters Australasia, she had also seen extreme cases of patients becoming seriously ill from over-the-counter diet pills.

Melbourne doctor and weight management expert Rick Kausman believes the ­industry “desperately” needs regulation, as it is dominated by those whose “first priority was not health and wellbeing”.

Dr Kausman said there was “irrefutable evidence” almost everyone who went on a diet regained the weight, with up to two-thirds of people ending up heavier, because diets were impossible to sustain.

The Dietitians Association of Australia backed moves for regulation. But chief executive Clair Hewat said how this should happen was unclear.